Electrostatic discharge (ESD) is a momentary and sudden electric current that flows when an excess of electric charge, stored on an electrically insulated structure, finds a path to a structure at a different electrical potential, such as ground. ESD is particularly a serious concern with micro-electronic devices. The integrated circuits (IC) in these devices are made from semiconductor materials, such as silicon, and insulating materials, such as silicon dioxide, which can break down when exposed to high voltages.
ICs are protected against damage due to ESD by a variety of circuit techniques. However, for high voltage power rails, wherein the voltage provided by the power supply is greater than the maximum voltage supported by ESD protection components for reliable operation, current approaches for providing ESD protection are insufficient. Prior approaches suffer from latch-up (e.g., a particular type of short circuit that can occur in an improperly designed circuit), insufficient ESD protection, and size restrictions.